Magnetic tone generator for musical instruments



Dec. 15, 1964 TI 3,161,713

MAGNETIC TONE GENERATOR FOR MUSICAL INSTRUMENTS Filed Aug. 9, 1962 2 Sheets-Sheet l FIG. 1. 2/

. hi1 REED N\I\ ocmvs STRING FIG. 3.

KEYBOARD INVENTOE Lou/5 MARTINEZ BY HIS A TTOENEYS HARE/5, Klan; Ruseu. & KERN Dec. 15, 1964 MARTINEZ 3,161,713

MAGNETIC TONE GENERATOR FOR MUSICAL INSTRUMENTS Filed Aug. 9, 1962 2 Sheets-Sheet 2 FIG. 4.

4o 4/ 44 HM H W 7 IN VE NTOR. Lou/5 MARTINEZ BY H/S ATTORNEYS HA 12/215, K/EcH, RUSSELL (3 KER/v United States Patent 9 3,161,713 MA GNETIC TGNE GENERATGR FGR EEUSICAL KNSTRUM'ENTS Louis Martinez, Arlington, Caliii, assignor to Pantronie, Inc, Arlington, Caiii, a corporation of California Filed Aug. 9, 1962, Ser. No. 215,936 12 Qlairns. (Cl. 84-1.il1}

This invention relates to electrical musical instruments and, in particular, to a tone generator for use in organs and the like.

Organs require a large number of different tones, which may be produced by individual electronic tone generators or oscillators, resulting in a large number of such tone generators per instrument Hence economy and simplicity of the tone generator circuitry and size of the unit are primary considerations in the design of electric instruments. Of course, stabiiity, waveform, tuning range, variety of outputs and reliability are also sought in the design of the instrument.

It is an object of the invention to provide a new and improved electronic tone generator for use in musical instruments including a magnetic core with one or more windings thereon and with a pair of current switching devices and a voltage source connected thereto to provide a voltage tunable oscillator. A further object is to provide such a tone generator which produces different types of tone at various points of the windings, providing a plurality of tones at a single frequency of the tone generator. to provide a magnetic multivibrator which is tuned by varying the supply voltage thereto and which produces a variety of output tones from the winding or windings on the core.

It is an object of the invention to provide an electric musical instrument utilizing such a tone generator in conjunction with one or more keyboard switches for actuating the generator and coupling one or more of the outputs to an amplifier and speaker.

It is an object of the invention to provide an elec tronic tone generator for a musical instrument including a magnetic multivibrator having a core, a tapped winding on' the core, and a pair of current switching elements for alternately completing a circuit through each portion of the tapped winding, an output winding on the core, and means for connecting a DO actuating voltage to the multivibrator including means for varying the magnitude of the voltage to adjust the frequency of the tones generated to generate a woodwind-type tone at the output winding and a reed-type tone at an end of the tapped vwinding and a string-type tone at a tap of the tapped winding. A further object is to provide such a generator in which the current switching elements may be tunnel diodes, transistors, vacuum tubes, or similar devices.

It is a particular object of the invention to provide a tone generator including a magnetic core having a first power winding, a second control winding and a third output winding thereon, a pair of transistors, means for connecting the transistors to circuit ground, to the first power winding and to the second control winding, means for connecting a DC. voltage source to a tap of the first winding for actuating the tone generator, and means for varying the voltage at the tap to adjust the frequency of the tones generated to provide a woodwind-type tone at the third output winding and a reed-type tone at an end of the first winding and a string-type tone at a tap of the first winding. A further object is to provide such a tone generator which may have a bias circuit in the form of a resistor between taps on the first and second windings to produce an extended tuning range.

A further object of the invention is to provide a tone A particular object of the invention is 3,151,713 Patented Dec. 15, 1964 generator which may be actuated with a single magnitude of voltage to provide a single pitch or which may be actuated with a selected one of a plurality of voltage magnitudes to provide a selected one of a plurality of corresponding pitches.

A further object is to provide a tone generator which may be turned off and on by controlling the supply voltage thereto or which may be permitted to run continuously with the outputs being connected and disconnected by the musician. An additional object is to provide a tone generator that may be tuned by varying the appded voltage and/or by varying the magnetic flux path.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. The drawing merely shows and the description merely describes preferred embodiments of the present invention which are given by way of illustration or example.

In the drawing:

FIG. 1 is a schematic diagram of a preferred form of the tone generator of the invention;

FIGS. 2, 4 and 5 are schematic diagrams of alternative forms of the tone generator;

FIG. 3 is a block diagram of an electric musical in strument incorporating the tone generator of the invention.

The circuit of FIG. 1 includes a magnetic multivibrator 7 with a voltage supply section 8 and an output section 9. A magnetic core 10 has windings 11, 12, 13 thereon with the collectors of transistors 14, 15 connected to the winding 11 and with the bases of the transistors connected to the winding 12. -The emitters are connected together and to circuit ground. The negative voltage from the section 8 is connected to the center tap of the winding 11 which in turn is connected to the center tap of the winding 12 through a resistor 16. A bias voltage for the transistors is developed across the resistor 16.

A DC. voltage at terminal 17 is applied to the winding 11 through one or more of switches 18, 19, 20 and variable or fixed resistors 21, 22, 23. The frequency of oscillation of the multivibrator and hence the pitch of the tone generator varies as a function of the magnitude of the DC. voltage and as a function of the effective magnetic core area and as a function of the value of the resistor 16. Coarse tuning is preferably carried out by varying the magnetic core structure and the value of the resistor 16 and fine tuning by varying the resis tors in the voltage supply circuit.

In the circuit of FIG. 1, each of switches 18, 19, 20 represents a keyboard actuated switch for a particular note. The particular circuit shown can be used to provide any one of three notes or pitches, depending upon the particularly switch being closed. In alternative forms, one, two or four or more switches may be utilized in the voltage supply section resulting in a tone generator which produces one, two or four or more different pitches or notes.

Three distinctive type of tones are produced directly by the tone generator of the invention. The winding 13 produces a woodwind-type of tone. A reed-type tone is provided at either end of the winding 11 and a stringtype tone is provided at a tap on the winding 11, normally the center tap. The fundamental pitch of the string-type tone is one octave above the woodwind and reed tones and is indicated on FIG. 1 as an octave string. Variations in tone quality may be obtained by utilizing taps on the winding 11 other than the center tap. Other tones such as flute, oboe, etc., may be obtained by filtering the basic waveforms in appropriate R-L-C networks.

v A musical instrument incorporating the tone generator of FIG. 1 is shown in FIG. 3. A keyboard 39 includes the switch for connecting the D.C. voltage to the tone generator 31. The various outputs from the tone generator are connected to a tone voicing unit 32 which may correspond to the stop selection switches of the organ. The selected tone signals are coupled as an input to an amplifier 33 which drives the speaker 34, providing the complete musical instrument.

Various modifications may be made in the circuit of FIG. 1 including modifications in the magnetic multivibrator. Npn or pnp type transistors as well as other switching devices, typically vacuum tubes and tunnel diodes, may be utilized. A modified form of the tone generator is shown in FIG. 2 in which elements corresponding to those of FIG. 1 are identified by the same reference numerals. The resistor 16 has been omitted and the center tap of the winding is connected to circuit ground. With this arrangement, the range of tuning available by change of voltage at the center tap of the winding 11 is relatively small.

The tone generator of FIG. 2 is turned on by a switch 40 when the entire instrument is turned on and runs continuously. The generator provides only a single tone which is adjusted by the variable resistor 41 in the D.C. supply line or by varying the core area. The generator is keyed by switches 42, 43, 44 in the output lines from the windings 11, 13 and 12, respectively, these switches being actuated by the keyboard.

The tone voicing unit 32 provides for frequency filtering of one or more of the types of tones produced by the tone generator and also permits combination of the tones to provide other tonal effects.

Another alternative form of the tone generator is shown in FIG. 4. This circuit is similar to that of FIG. 2, with the transistors 14, connected differently in the multivibrator circuit. The transistor bases are connected together and to circuit ground and the transistor emitters are connected to the winding 12 which provides the switching voltages for the multivibrator.

The tone generator circuit of FIG. 5 utilizes tunnel diodes 54, 55 as the current switching elements. The diodes are connected in series opposition across the winding 11 with the common point of the interconnected diodes connected to circuit ground. The control voltage winding 12 is not necessary in this embodiment. The generator is turned on by switch 56 and the variable resistor 57 provides for fine tuning, as in the preceding embodiments. It should be noted that when the woodwind-type tone is not required, the winding 13 may be omitted.

The tone generator of the invention is small, compact and inexpensive. It is reliable and stable in pitch, contains no capacitors, and is not affected by variations in transistor characteristics or core inductance. It is well adapted to mass production techniques and printed circuitry. The magnetic core may be a deposited ferrite material or a pressed ferrite block or a conventional iron lamination. The frequency of a generator may be tuned over a range of two octaves; hence only a few different units are required in an organ.

Although exemplary embodiments of the invention have been disclosed and discussed, it will be understood that other applications of the invention are possible and that the embodiments disclosed may be subjected to various changes, modifications and substitutions without necessarily departing from the spirit of the invention.

I claim as my invention:

1. In a musical instrument including an electronic tone generator, the combination of:

a magnetic multivibrator having a core, a tapped winding on said core, and a pair of current switching elements for alternately completing a circuit through each portion of said winding;

means for connecting a direct current actuating voltage to said multivibrator, including means for varying the magnitude of the voltage to adjust the fre-- quency of the tones generated, to generate a reedtype tone at an end of said winding and a stringtype tone at a tap of said winding;

amplifier means;

a speaker;

means for selectively connecting said winding to said amplifier means; and

means for connecting the amplifier means output to said speaker.

2. In a musical instrument including an electronic tone generator, the combination of:

a magnetic multivibrator having a core, a tapped winding on said core, and a pair of current switching elements for alternately completing a circuit through each portion of said tapped winding;

an output winding on said core;

means for connecting a direct current actuating voltage to said multivibrator, including means for varying the magnitude of the voltage to adjust the frequency of the tones generated, to generate a woodwind-type tone at said output winding and a reedtype tone at an end of said tapped winding and a string-type tone at a tap of said tapped winding;

amplifier means;

a speaker;

means for selectively connecting said windings .to said amplifier means; and

means for connecting the amplifier means output to said speaker.

3. In a musical instrument including an electronic tone generator, the combination of:

a magnetic multivibrator having a core, a tapped winding on said core, and a pair of current switching elements for alternately completing a circuit through each portion of said tapped winding;

an output winding on said core;

a direct current voltage source terminal;

a plurality of variable resistances;

a corresponding plurality of switches;

circuit means for connecting said switches and resistors between said source terminal and said multivibrator, with each switch serving to actuate the tone generator at a difierent frequency which varies as a function of the voltage at said multivibrator and to generate a woodwind-type tone at said output winding and a reed-type tone at an end of said tapped winding and a string-type tone at a tap of said tapped winding;

amplifier means;

a speaker;

means for selectively connecting said windings to said amplifier means; and

means for connecting the amplifier means output to said speaker.

4. In a musical instrument including an electronic tone generator, the combination of:

a magnetic multivibrator having a core, a tapped winding on said core, and a pair of current switching elements for alternately completing a circuit through each portion of said tapped winding;

an output winding on said core;

means for connecting a direct current actuating voltage to said multivibrator, including means for varying the magnitude of the voltage to adjust the frequency of the tones generated, to generate a woodwind-type tone at said output winding and a reed-type tone at an end of said tapped winding and a string-type tone at a tap of said tapped winding;

amplifier means;

a speaker;

means for selectively connecting said windings to said amplifier means including first, second and third switches connected between said amplifier means and said output winding, said end and said tap, respectively; and

means for connecting the amplifier means output to said speaker.

5. In a musical instrument including an electronic tone generator, the combination of:

a magnetic multivibrator having a core, a tapped winding on said core, and a pair of tunnel diodes connected in series opposition across said tapped winding for alternately completing a circuit through each portion of said tapped winding to the common point of said diodes;

an output winding on said core;

means for connecting a direct current actuating voltage to said multivibrator, including means for varying the magnitude of the voltage to adjust the frequency of the tones generated, to generate a woodwind-type tone at said output winding and a reed-type tone at an end of said tapped winding and a string-type tone at a tap of said tapped winding;

ampliner means;

a speaker;

means for selectively connecting said windings to said amplifier means; and

means for connecting the amplifier means output to said speaker.

6. In a musical instrument including an electronic tone generator, the combination of:

a magnetic multivibrator having a core, a first tapped winding on said core, a second Winding on said core, and a pair of transistors connected in series opposition across said first winding and triggered by said second winding for alternately completing a circuit through each portion of said first tapped winding;

a third output winding on said core;

means for connecting a direct current actuating voltage to said multivibrator, including means for varying the magnitude of the voltage to adjust the frequency of the tones generated, to generate a woodwind-type tone at said output winding and a reedstype tone at an end of said tapped winding and a string-type tone at a tap of said tapped winding;

amplifier means;

a speaker;

means for selectively connecting said windings to said amplifier means; and

means for connecting the amplifier means output to said speaker.

7. In a musical instrument including an electronic tone generator, the combination of:

a magnetic core having first, second and third windings thereon;

a pair of transistors;

means for connecting the transistors in series opposing across said first winding with the common point connected to circuit ground, and with the remaining elements connected to said second winding;

means for connecting a direct current voltage source to a tap of said first winding for actuating the tone generator, including means for varying the voltage at the tap to adjust the frequency of the tones generated, to generate a woodwind-type tone at said third winding and a reed-type tone at an end of said first winding and a string-type tone at a tap of said first winding;

amplifier means;

a speaker;

means for selectively connecting said windings to said amplifier means; and

means for connecting the amplifier means output to said speaker.

8. In a musical instrument including an electronic tone generator, the combination of:

a magnetic core having first, second and third windings thereon;

a pair of transistors;

means for connecting the transistors in series opposing across said first winding with the common point connected to circuit ground, and with the remaining elements connected to said second winding;

means for connecting a direct current voltage source to a tap of said first winding for actuating the tone generator, including means for varying the voltage at the tap to adjust the frequency of the tones generated, to generate a woodwind-type tone at said third winding and a reed-type tone at an end of said first winding and a string-type tone at a tap of said first winding;

a bias resistor connected between said tap of said first winding and a tap of said second winding;

amplifier means;

a speaker;

means for selectively connecting said windings to said amplifier means; and

means for connecting the amplifier means output to said speaker.

9. In a musical instrument including an electronic tone generator, the combination of:

a magnetic core having first, second and third windings thereon;

a pair of transistors;

means for connecting the transistors in series opposing across said first winding with the common point connected to circuit ground, and with the remaining elements connected to said second winding;

means for connecting a directcurrent voltage source to a tap of said first winding for actuating the tone generator, including means for varying the voltage at the tap to adjust the frequency of the tones generated, to generate a woodwind-type tone at said third winding and a reed-type tone at an end of said first winding and a string-type tone at a tap of said first winding;

means for connecting one point of said second winding to circuit ground;

amplifier means;

a speaker;

means for selectively connecting said windings to said amplifier means; and

means for connecting the amplifier means output to said speaker.

10. In a musical instrument including an electronic tone generator, the combination of:

means for connecting the transistor emitters to circuit ground, the collectors to said first winding, and the bases to said second winding;

means for connecting a direct current voltage source to a tap of said first winding for actuating the tone generator, including means for varying the voltage at the tap to adjust the frequency of the tones generated, to generate a woodwind-type tone at said third winding and a reed-type tone at an end of said first winding and string-type tone at a tap of said first winding;

amplifier means;

a speaker;

means for selectively connecting said windings to said amplifier means; and

means for connecting the amplifier means output to said speaker.

11. In a musical instrument including an electronic tone generator, the combination of:

a magnetic core having first, second and third windings thereon;

a pair of transistors;

means for connecting the transistor bases to circuit ground, the collectors to said first winding, and the emitters to said second winding;

means for connecting a direct current voltage source to to a tap of said first winding for actuating the tone generator, including means for varying the voltage at the tap to adjust the frequency of the tones generated, to generate a woodwind-type tone at said third winding and a reed-type tone at an end of said first winding and a string-type tone at a tap of said first Winds;

amplifier means;

a speaker;

means for selectively connecting said windings to said amplifier means; and

means for connecting the amplifier means output to said speaker.

12. In a musical instrument including an electronic tone generator, the combination of:

a magnetic core having first and second windings therea pair of tunnel diodes;

means for connecting said diodes in series opposing to said first winding and the common point to circuit ground;

means for connecting a direct current voltage source to a tap of said first winding for actuating the tone generator, including means for varying the voltage at the tap to adjust the frequency of the tones generated, to generate a woodwind-type tone at said second winding and a reed-type tone at an end of said first winding and a string-type tone at a tap of said first winding; amplifier means; a speaker; means for selectively connecting said windings to said amplifier means; and means for connecting the amplifier means output to said speaker.

References Cited in the file of this patent UNITED STATES PATENTS 2,854,580 Uchrin et a1 Sept. 30, 1958 2,906,157 Peterson Sept. 29, 1959 2,959,744 Wengryn Nov. 8, 1960 OTHER REFERENCES Electrical Engineering (magazine), February 1962, vol.

81, No. 2 (page 112 relied on). 

1. IN A MUSICAL INSTRUMENT INCLUDING AN ELECTRONIC TONE GENERATOR, THE COMBINATION OF: A MAGNETIC MULTIVIBRATOR HAVING A CORE, A TAPPED WINDING ON SAID CORE, AND A PAIR OF CURRENT SWITCHING ELEMENTS FOR ALTERNATELY COMPLETING A CIRCUIT THROUGH EACH PORTION SAID WINDING; MEANS FOR CONNECTING A DIRECT CURRENT ACTUATING VOLTAGE TO SAID MULTIVIBRATOR, INCLUDING MEANS FOR VARYING THE MAGNITUDE OF THE VOLTAGE TO ADJUST THE FREEQUENCY OF THE GENERATED, TO GENERARTED A REEDTYPE TONE AT AN END OF SAID WINDING AND A STRING TYPE TONE AT A TAP OF SAID WINDING; AMPLIFIER MEANS; A SPEAKER; MEANS FOR SELECTIVELY CONNECTING SAID WINDING TO SAID AMPLIFIER MEANS; AND MEANS FOR CONNECTING THE AMPLIFIER MEANS OUTPUT TO SAID SPEAKER. 